The present invention relates to an image analyzing apparatus and, particularly, to such an apparatus which enables unskilled users to define a plurality of regions of interest in a density profile in a desired manner and to effect quantitative analysis on the regions of interest.
A radiographic diagnosis system using as a detecting material for detecting radiation a stimulable phosphor which can absorb, store and record the energy of radiation when it is irradiated with radiation and when it is then stimulated by an electromagnetic wave having a specified wavelength, can release stimulated emission whose light amount corresponds to the amount of radiation with which it was irradiated is known, which comprises the steps of storing and recording the energy of radiation transmitted through an object in a stimulable phosphor, scanning a stimulable phosphor layer with an electromagnetic wave to stimulate the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the digital image signals and reproducing a radiation image on a display means such as a CRT or a recording material such as a photographic film (For example, Japanese patent Application Laid Open Nos. 55-12429, 55-116340, 55-163472, 56-11395, 56-104645 and the like.).
There is also known an autoradiography system comprising the steps of employing a similar stimulable phosphor as a detecting material for the radiation, introducing a radioactively labeled substance into an organism, using the organism or a part of the tissue of the organism as a specimen, placing the specimen and a stimulable phosphor sheet formed with a stimulable phosphor layer together in layers for a certain period of time, storing and recording radiation energy in a stimulable phosphor contained in the stimulable phosphor layer, scanning the stimulable phosphor layer with an electromagnetic wave to excite the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the obtained digital image signals, and reproducing an image on displaying means such as a CRT or the like or a photographic film (see for example, Japanese Patent Publication No. 1-60784, Japanese Patent Publication No. 1-60782, Japanese Patent Publication No. 4-3952 and the like).
There is further known a chemiluminescent detecting system using as a detecting material for detecting light a stimulable phosphor which can absorb, store and record the light energy when it is irradiated with light and when it is then stimulated by an electromagnetic wave having a specified wavelength, can release stimulated emission whose light amount corresponds to the amount of light radiation with which it was irradiated, which comprises the steps of selectively labeling a fixed high molecular substance such as a protein or a nucleic acid sequence with a labeling substance which generates chemiluminescent emission when it contacts a chemiluminescent substance, contacting the high molecular substance selectively labeled with the labeling substance and the chemiluminescent substance, storing and recording the chemiluminescent emission in the wavelength of visible light generated by the contact of the chemiluminescent substance and the labeling substance in a stimulable phosphor layer formed on a stimulable phosphor sheet, scanning the stimulable phosphor layer with an electromagnetic wave to stimulate the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the digital image signals and reproducing an image on a display means such as a CRT or a recording material such as a photographic film, and obtaining information relating to the high molecular substance such as genetic information (For Example, U.S. Pat. No. 5,028,793, British Patent Publication GB No. 2,246,197A and the like).
There are further known an electron microscope detecting system and a radiographic diffraction image detecting system comprising the steps of employing, as a detecting material for an electron beam or radiation, a stimulable phosphor which can absorb and store the energy of an electron beam or radiation upon being irradiated therewith and release a stimulated emission whose amount is proportional to that of the received electron beam or radiation upon being stimulated with an electromagnetic wave having a specific wavelength range, irradiating a metal or nonmetal specimen with an electron beam and effecting elemental analysis, composition analysis or structural analysis of the specimen by detecting a diffraction image or a transmission image, or irradiating the tissue of an organism with an electron beam and detecting an image of the tissue of the organism, or irradiating a specimen with radiation, detecting a radiographic diffraction image and effecting structural analysis of the specimen (see for example, Japanese Patent Application Laid Open No. 61-51738, Japanese Patent Application Laid Open No. 61-93538, Japanese Patent Application Laid Open No. 59-15843 and the like).
Unlike the system using a photographic film, according to these systems using the stimulable phosphor as a detecting material for an image, development which is chemical processing, becomes unnecessary. Further, it is possible reproduce a desired image by effecting image processing on the obtained image data and effect quantitative analysis using a computer. Use of a stimulable phosphor in these processes is therefore advantageous.
On the other hand, a fluorescence system using a fluorescent substance as a labeling substance instead of a radioactively labeled substance in the autoradiography system is known. According to this system, it is possible to study a genetic sequence, the expression level of a gene and to effect the separation or identification of protein or the estimation of the molecular weight or properties of protein or the like. For example, this system can perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis after a fluorescent dye was added to a solution containing a plurality of DNA fragments to be distributed or distributing a plurality of DNA fragments on a gel support containing fluorescent dye or dipping a gel support on which a plurality of DNA fragments have been distributed by means of electrophoresis in a solution containing fluorescent dye, thereby labeling the electrophoresis-distributed DNA fragments, exciting the fluorescent dye by a stimulating ray to cause it to release a fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the DNA on the gel support. This system also performs a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis, denaturing the DNA, transferring at least a part of the denatured DNA fragments onto a transfer support such as a nitrocellulose support by the Southern-blotting method, hybridizing a probe prepared by labeling target DNA and DNA or RNA complementary thereto with the denatured DNA fragments, thereby selectively labeling only the DNA fragments complementary to the probe DNA or probe RNA, exciting the fluorescent dye by a stimulating ray to cause it to release a fluorescent light, detecting the released fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This system can further perform a process including the steps of preparing a DNA probe complementary to DNA containing a target gene labeled by a labeling substance, hybridizing it with DNA on a transfer support, combining an enzyme with the complementary DNA labeled by a labeling substance, causing the enzyme to contact a fluorescent substrate, transforming the fluorescent substrate to a fluorescent substance having a property to release fluorescent light, exciting the thus produced fluorescent substance by a stimulating ray to release fluorescent light, detecting the fluorescent light to produce an image and detecting the distribution of the target DNA on the transfer support. This fluorescence detecting system is advantageous in that a genetic sequence or the like can be easily detected without using a radioactive substance.
In order to quantitatively analyze, an image analyzing apparatus used with these systems is constituted so as to be able to produce a density profile of a specific image region in an obtained image and display it on a display means such as a CRT.
More specifically, the base sequence of DNA is determined by means of electrophoresis in accordance with the steps of dropping a plurality of specimens containing DNA fragments containing a specific gene onto a gel support medium at constant intervals, separating and distributing them by means of electrophoresis, denaturing them by alkali processing to form single-stranded DNA, fixing the denatured DNA fragments onto a filter according to the known Southern blot hybridization method, hybridizing them with labeled DNA or RNA which is complementary to the DNA containing the specific gene to label the DNA fragments containing the specific gene and imaging the distribution of the labeling substance. In this case, the lower the molecular weight of the DNA is, the longer distance it travels. The images corresponding to the respective specimens are therefore distributed one-dimensionally, namely, lane-like and, therefore, the image obtained by electrophoresis includes a plurality of lane-like images equally spaced and parallel to each other. It is often required to produce a density profile of lane-like image regions in the thus obtained image for determining the base sequence of DNA by means of electrophoresis.
In the thin-layer chromatography (TLC) widely used in research into drug metabolism, how a drug labeled with a labeling substance and introduced into a test animal changes in the body of the animal is analyzed by collecting specimens of urine, blood, tissue or the like from a specific region of the animal at predetermined time intervals, processing the specimens in a predetermined manner and dropping the processed specimens at predetermined positions at regular intervals on a TLC plate which is formed by coating a glass plate with powders of silica gel. The TLC plate is dipped in a distribution solvent and the specimens are chromatographically distributed, thereby forming separate spots for individual components of the specimens. As a result, the specimens collected at predetermined time intervals are distributed one-dimensionally, namely, lane-like. A so-obtained image therefore includes a plurality of lane-like images equally spaced and parallel to each other. In this case, for determining how the drug was metabolized, it is often required to produce a density profile of lane-like image regions in the thus obtained image.
In this manner, it is often required to define a region of interest in a density profile displayed on a display means and obtain the sum value of pixel density in the region of interest in order to quantitatively analyze an image and, therefore, an image analyzing apparatus used with these systems is constituted so as to be able to define an arbitrary region in a density profile displayed on a display means as a region of interest.
If an arbitrary region in a density profile displayed on a display means can be defined as a region of interest, it is possible to quantitatively analyze an arbitrary region. This is very convenient. However, since one pixel can belong to two or more regions of interest, the following problem occurs.
Specifically, in the field of thin-layer chromatography, there is known a quantitative analysis technique including the steps of dropping drug onto a silica gel layer formed on a glass plate, chromatographically distributing it with a solvent, scratching off the silica gel, dissolving each silica gel fragment into a separate solvent, and effecting a quantitatively analysis using a liquid scintillation counter. In such a quantitative analysis technique, regions continuously adjacent to each other are defined as regions of interest by scratching off the silica gel to form silica gel fragments, thereby effecting a quantitative analysis. To the contrary, when a similar quantitative analysis is effected on an image produced using a stimulable phosphor sheet as a detecting material for the image, instead of scratching off the silica gel fragments, it is indispensable to define regions continuously adjacent to each other as regions of interest in a density profile displayed on a display means, thereby effecting a quantitative analysis. However, since all conventional image analyzing apparatuses are constituted so as to enable an arbitrary region to be defined as a region of interest in a density profile displayed on a display means, the user has to observe the image displayed on a display means, specify a pixel adjacent to a region of interest previously defined using a mouse, drag the mouse to the terminal end point of the region of interest to be defined in such a manner that no pixel is included in two or more regions of interest, thereby defining a region of interest. This operation is extremely troublesome and it is difficult for an unskilled user to define a region of interest in the desired manner.
It is therefore an object of the present invention to provide an image analyzing apparatus which enables unskilled users to define a plurality of regions of interest in a density profile in a desired manner and to effect quantitative analysis on the regions of interest.
The above and other objects of the present invention can be accomplished by an image analyzing apparatus comprising image data storing means for storing image data, image data memory means for two-dimensionally and temporarily storing at least a part of image data stored in the image data storing means and input means through which instruction signals are input, and being adapted for displaying an image on display means based on the image data temporarily stored in the image data memory means and effecting a quantitative analysis, said image analyzing apparatus further comprising profile data producing means for producing profile data of density in a predetermined image region based on the image data temporarily stored in the image data memory means and storing them in the image data memory means and region-of-interest defining means for defining a region of interest in a density profile displayed on the display means based on the profile data produced by the profile data producing means and stored in the image data memory means, said region-of-interest defining means being constituted so as to define a region of interest when an instruction signal is received through the input means to define a new region of interest in such a manner that in the case where a single region of interest has been previously defined, if one end point of the region of interest to be newly defined is located in the previously defined region of interest and another end point of the region of interest to be newly defined is not located in the previously defined region of interest, it determines the other end point of the region of interest to be newly defined in accordance with the instruction signal and defines a new region of interest so as to be continuously adjacent to the previously defined region of interest irrespective of an input coordinate value of the one end point of the region of interest to be newly defined.
According to the present invention, the region-of-interest defining means is constituted so as to respond to an instruction signal to define a new region of interest received through the input means by defining a new region of interest in such a manner that in the case where a single r egion of interest has been previously defined, if one end point of the region of interest to be newly defined is located in the previously defined region of interest and an other end point of the region of interest to be newly defined is not located in the previously defined region of interest, it determines the other end point of the region of interest to be newly defined in accordance with the instruction signal and defines a new region of interest so as to be continuously adjacent to the previously defined region of interest irrespective of an input coordinate value of the one end point of the new region of interest. Therefore, it is unnecessary for the user to carefully specify a pixel adjacent to the previously defined region of interest using a mouse and drag the mouse to the terminal end point of the region of interest to be newly defined in order to define a new region of interest and since it is possible to easily define a new region of interest so as to be continuously adjacent to the previously defined region of interest without exercising particular care, even an unskilled user can define a new region of interest so as to be continuously adjacent to the previously defined region of interest in the desired manner.
In a preferred aspect of the present invention, said region-of-interest defining means is constituted so as to compare the coordinate value of the one end point of the new region of interest input through the input means with coordinate values of opposite end points of the previously defined region of interest, thereby defining the new region of interest so as to be continuously adjacent to the previously defined region of interest, if the one end point of the region of interest to be newly defined is located in the previously defined region of interest and the other end point of the region of interest to be newly defined is not located in the previously defined region of interest.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that if one end point of a region of interest to be newly defined is located in the previously defined region of interest and the other end point of the region of interest to be newly defined is not located in the previously defined region of interest, it determines a coordinate value of the other end point of the new region of interest in accordance with the instruction signal input through the input means and sets the coordinate value XS of the one end point of the new region of interest to be YT+1 based on a coordinate value YT of one of the end points of the previously defined region of interest, and so that if one end point of a region of interest to be newly defined is not located in the previously defined region of interest and the other end point of the region of interest to be newly defined is located in the previously defined region of interest, it sets the coordinate value XT of the other end point of the new region of interest to be YSxe2x88x921 based on a coordinate value YS of the other end point of the previously defined region of interest.
According to this preferred aspect of the present invention, it is unnecessary for the user specify a pixel adjacent to the previously defined region of interest using a mouse and drag the mouse to the terminal end point of a region of interest to be defined in order to define a new region of interest while exercising particular care and it is possible to easily define a new region of interest so as to be continuously adjacent to the previously defined region of interest. Therefore, even an unskilled user can define a new region of interest so as to be continuously adjacent to the previously defined region of interest in a desired manner.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so as to define the new region of interest in accordance with coordinate values of opposite end points of the new region of interest input through the input means, if the opposite end points of the region of interest to be newly defined are not located in the previously defined region of interest and the region of interest to be newly defined does not include the previously defined region of interest.
According to this preferred aspect of the present invention, the region-of-interest defining means is constituted so as to define the new region of interest in accordance with coordinate values of opposite end points of the new region of interest input through the input means, if the opposite end points of the region of interest to be newly defined are not located in the previously defined region of interest and the region of interest to be newly defined does not include the previously defined region of interest. Therefore, if the user wishes to define a new region of interest so as to be spaced from the previously defined region of interest, a plurality of regions of interest can be defined in a density profile displayed on the display means merely by inputting an instruction to define a new region of interest so that the opposite end points of the new region of interest are not located in the previously defined region of interest and that the new region of interest does not include the previously defined region of interest.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that in the case where two or more regions of interest have been previously defined, if a region of interest to be newly defined does not include any one of the previously defined regions of interest, one end point of the region of interest to be newly defined is located in one of the previously defined regions of interest and an other end point of the region of interest to be newly defined is not located in any one of the previously defined regions of interest, it defines the new region of interest so that the one end point of the new region of interest is continuously adjacent to the previously defined region of interest in which it is located and that a coordinate value of the other end point of the new region of interest equals a coordinate value of the other end point of the new region of interest input through the input means.
According to this preferred aspect of the present invention, in the case where two or more regions of interest have been previously defined, if a region of interest to be newly defined does not include any one of the previously defined regions of interest, one end point of the region of interest to be newly defined is located in one of the previously defined regions of interest and an other end point of the region of interest to be newly defined is not located in any one of the previously defined regions of interest, said region-of-interest defining means defines the new region of interest so that the one end point of the new region of interest is continuously adjacent to the previously defined region of interest in which it is located and that a coordinate value of the other end point of the new region of interest equals to a coordinate value of the other end point of the new region of interest input through the input means. Therefore, it is unnecessary for a user specify a pixel adjacent to the previously defined region of interest using a mouse and drag the mouse to the terminal end point of a region of interest to be defined in order to define a new region of interest while exercising particular care and it is possible to easily define a new region of interest so as to be continuously adjacent to the previously defined region of interest. Therefore, even an unskilled user can define a new region of interest so as to be continuously adjacent to the previously defined region of interest in the desired manner.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in one of the previously defined regions of interest and the other end point of the region of interest to be newly defined is not located in any one of the previously defined regions of interest, it defines the new region of interest to be continuously adjacent to the previously defined region of interest by comparing a coordinate value of the one end point of the region of interest to be newly defined input through the input means with coordinate values of opposite end points of the previously defined region of interest in which the one end point of the region of interest to be newly defined is located.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in a first previously defined region of interest and the other end point of the region of interest to be newly defined is located in a second previously defined region of interest, it defines the new region of interest so that the one end point thereof is continuously adjacent to the first previously defined region of interest and that the other end point thereof is continuously adjacent to the second previously defined region of interest.
According to this preferred aspect of the present invention, in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in a first previously defined region of interest and the other end point of the region of interest to be newly defined is located in a second previously defined region of interest, said region-of-interest defining means defines the new region of interest so that the one end point thereof is continuously adjacent to the first previously defined region of interest and that the other end point thereof is continuously adjacent to the second previously defined region of interest. Therefore, even when a user does not specify pixels adjacent to the first previously defined region of interest and the second previously defined region of interest to define a new region of interest while exercising particular care, it is possible to easily define a new region of interest so as to be continuously adjacent to the first previously defined region of interest and the second previously defined region of interest and, therefore, even an unskilled user can define a new region of interest in a density profile so as to be continuously adjacent to the plurality of previously defined regions of interest in the desired manner.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in the first previously defined region of interest and the other end point of the region of interest to be newly defined is located in the second previously defined region of interest, it defines the new region of interest to be continuously adjacent to the first previously defined region of interest and the second previously defined region of interest by comparing a coordinate value of the one end point of the region of interest to be newly defined input through the input means with coordinate values of opposite end points of the first previously defined region of interest and comparing a coordinate value of the other end point of the region of interest to be newly defined input through the input means with opposite end points of the second previously defined region of interest.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in the first previously defined region of interest and the other end point of the region of interest to be newly defined is located in the second previously defined region of interest, it sets a coordinate value XS of the one end point of the region of interest to be newly defined to be equal to YT+1 based on a coordinate value YT of the one end point of the first previously defined region of interest and sets a coordinate value XT of the other end point of the region of interest to be newly defined to be equal to YSxe2x88x921 based on a coordinate value YS of the other end point of the second previously defined region of interest.
According to this preferred aspect of the present invention, in the case where two or more regions of interest have been previously defined, if the region of interest to be newly defined does not include any one of the previously defined regions of interest, the one end point of the region of interest to be newly defined is located in the first previously defined region of interest and the other end point of the region of interest to be newly defined is located in the second previously defined region of interest, said region-of-interest defining means sets a coordinate value XS of the one end point of the region of interest to be newly defined to be equal to YT+1 based on a coordinate value YT of the one end point of the first previously defined region of interest and sets a coordinate value XT of the other end point of the region of interest to be newly defined to be equal to YSxe2x88x921 based on a coordinate value YS of the other end point of the second previously defined region of interest. Therefore, even when a user does not specify pixels adjacent to the first previously defined region of interest and the second previously defined region of interest to define a new region of interest while exercising particular care, it is possible to easily define a new region of interest so as to be continuously adjacent to the first previously defined region of interest and the second previously defined region of interest and, therefore, even an unskilled user can define a new region of interest in a density profile so as to be continuously adjacent to the plurality of previously defined region of interest in the desired manner.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that if a region of interest to be newly defined includes the previously defined region of interest, it judges that it is impossible to define a new region of interest and outputs re-definition signal.
According to this preferred aspect of the present invention, even when a user erroneously operates a mouse, an undesired region of interest can be prevented from being defined in accordance with an erroneous instruction of the user and the user can be warned.
In a further preferred aspect of the present invention, said region-of-interest defining means is constituted so that if a region of interest to be newly defined is included the previously defined region of interest, it judges that it is impossible to define a new region of interest and outputs re-definition signal.
According to this preferred aspect of the present invention, even when a user erroneously operates a mouse, an undesired region of interest can be prevented from being defined in accordance with an erroneous instruction of the user and the user can be warned.
In a further preferred aspect of the present invention, the image data are produced using a stimulable phosphor sheet.
In a further preferred aspect of the present invention, the image data are constituted by image data selected from a group consisting of autoradiographic image data, radiographic diffraction image data, electron microscopic image data, chemiluminescent image data and fluorescent image data.
In the present invention, the stimulable phosphor employed for producing autoradiographic image data, radiographic diffraction image data and an electron microscopic image data may be of any type insofar as it can store radiation energy or electron beam energy and can be stimulated by an electromagnetic wave to release the radiation energy or electron beam energy stored therein in the form of light. However, a stimulable phosphor which can be stimulated by light having a visible light wavelength is preferably employed. More specifically, preferably employed stimulable phosphors include alkaline earth metal fluorohalide phosphors (Ba1xe2x88x921,M2+x)F X:yA (where M2+ is at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd; X is at least one halogen selected from the group consisting of Cl, Br and I, A is at least one element selected from the group consisting of Eu, Tb, Ce, Tm, Dy, Pr, He, Nd, Yb and Er; x is equal to or greater than 0 and equal to or less than 0.6 and y is equal to or greater than 0 and equal to or less than 0.2) disclosed in U.S. Pat. No. 4,239,968, alkaline earth metal fluorohalide phosphors SrFX:Z (where X is at least one halogen selected from the group consisting of Cl, Br and I; and Z is at least one of Eu and Ce) disclosed in Japanese Patent Application Laid Open No. 2-276997, europium activated complex halide phosphors BaFX xNaXxe2x80x2:aEu2+ (where each of X and Xxe2x80x2 is at least one halogen selected from the group consisting of Cl, Br and I; x is greater than 0 and equal to or less than 2; and y is greater than 0 and equal to or less than 0.2) disclosed in Japanese Patent Application Laid Open No. 59-56479, cerium activated trivalent metal oxyhalide phosphors MOX:xCe (where M is at least one trivalent metal selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Bi; X is at least one halogen selected from the group consisting of Br and I; and x is greater than 0 and less than 0.1) disclosed in Japanese Patent Application Laid Open No. 58-69281, cerium activated rare earth oxyhalide phosphors LnOX:xCe (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is at least one halogen selected from the group consisting of Cl, Br, and I; and x is greater than 0 and equal to or less than 0.1) disclosed in U.S. Pat. No. 4,539,137 and europium activated complex halide phosphors MIIFXaMIXxe2x80x2bMxe2x80x2IIXxe2x80x32cMIIIXxe2x80x2xe2x80x33xA:yEu2+ (where MII is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; MI is at least one alkaline metal selected from the group consisting of Li, Na, K, Rb and Cs; Mxe2x80x2II is at least one divalent metal selected from the group consisting of Be and Mg; MIII is at least one trivalent metal selected from the group consisting of Al, Ga, In and Tl; A is at least one metal oxide; X is at least one halogen selected from the group consisting of Cl, Br and I; each of Xxe2x80x2, Xxe2x80x3 and Xxe2x80x2xe2x80x3 is at least one halogen selected from the group consisting of F, Cl, Br and I; a is equal to or greater than 0 and equal to or less than 2; b is equal to or greater than 0 and equal to or less than 10-2; c is equal to or greater than 0 and equal to or less than 10-2; a+b+c is equal to or greater than 10-2; x is greater than 0 and equal to or less than 0.5; and y is greater than 0 and equal to or less than 0.2) disclosed in U.S. Pat. No. 4,962,047.
In the present invention, the stimulable phosphor employed for producing a chemiluminescent image may be of any type insofar as it can store the energy of light having a visible light wavelength and can be stimulated by an electromagnetic wave to release the energy of light having a visible light wavelength stored therein in the form of light. However, a stimulable phosphor which can be stimulated by light having a visible light wavelength is preferably employed. More specifically, preferably employed stimulable phosphors include at least one selected from the group consisting of metal halophosphates, rare-earth-activated sulfide-host phosphors, aluminate-host phosphors, silicate-host phosphors, fluoride-host phosphors and mixtures of two, three or more of these phosphors. Among them, rare- rare-earth-activated sulfide-host phosphors are more preferable and, particularly, rare-earth-activated alkaline earth metal sulfide-host phosphors disclosed in U.S. Pat. Nos. 5,029,253 and 4,983,834 are most preferable.
The above and other objects and features of the present invention will become apparent from the following description made with reference to the accompanying drawings.